A TOP-secret letter between TV personality Suzie Wilks and her estranged husband, businessman Nick OHalloran - believed to have been leaked by his most recent former flame - is at the centre of a Supreme Court battle.

A Supreme Court judge found last week that its “highly sensitive” contents could irreparably damage the reputation of Mr O’Halloran and banned his ex, Rachel Roche, from publishing or sharing the document.

Today the matter was heard under a shroud of secrecy in a court closed to the public to protect the contents of the confidential letter.

Mr O’Halloran last week succeeded in an urgent application for an injunction to stop a Sydney newspaper from publishing the details of the letter - which Justice Peter Almond described as “sufficiently grave to warrant protection” - after he was contacted for comment.

The judge said Mr O’Halloran, the co-founder of a new technologies company, kept the letter in safe custody and that Ms Roche was the only likely person who could have obtained possession of the letter.

“I am satisfied the (Ms Roche) in all likelihood made use of that information to disclose the contents to third parties and infer a threat to essentially damage the reputation of Mr O’Halloran (and) that she threatens to further make use by either disclosing the contents of the letter or disclosing the letter itself,” the judge said.

Justice Almond said it was not clear how Ms Roche came into possession of the letter, containing discussions of the “most personal and serious kind” between Mr O’Halloran and his wife, Ms Wilks, from whom he is currently separated.

The former renovation babe - who hosted a number of prime-time shows, including Changing Rooms, Our House and Postcards - split with her husband of two years in 2012, not long after the 2011 birth of their daughter, Ruby.

The contents of the letter are unknown and remain with the court in a sealed envelope.

Justice Almond said Mr O’Halloran clearly had an arguable case that communication of the letter amounted to the unauthorised disclosure of “protected matrimonial confidences”.

He said the letter’s contents could clearly damage Mr O’Halloran’s reputation to an extent that he would be unable to be compensated by money.

Ms Roche, who was banned from communicating the contents of the letter and ordered to hand over or destroy any copies, represented herself in court today, saying she wanted to be able to share her side of the story.

“What I have to say has ramifications for other people,” Ms Roche said before Justice Ann Ferguson ordered the court be closed.